Looking for some opinions,I've only ever installed "new work" style recessed lighting housing - even in remodel work. Just modified as necessary to fit

I recently installed a few small wall washers that were "old work" style recently and found they worked pretty well. I was always afraid the lip would never sit tight and flush with the ceiling - but not the case here.

Are the 5" and 6" "old work" as good as the small ones? Specifically Halo IC incandescent housings.

I've never had a problem with the old-work cans. I will second the advice on cutting the holes PRECISELY. I use a large carbide grit hoiesaw sold specifically for cutting these holes. Makes a nice clean, tight fitting hole, which is the key to getting the cans to suck up tight to the ceiling.

For plaster and lathe, I use the carbide grit hole saw, with a masonary bit in the arbor, first, for the plaster and switch to a carbide tipped hole saw for the lathe. For drywall I use the carbide tipped.

I started using one of those adjustable HolePro X-200 kits with the carbide bits and dust collector last year, mainly because I could never find carbide tipped recessed light hole saws for the Halo 5-inch remodel cans or those really tiny Lightolier remodels. I believe they are 3-inch. I still have the older Greenlee recessed light hole saws that I’ve used for years as backups.With the popularity of the 5-inch cans, I can't understand why Greenlee, Milwaukee or Lennox hasn't made a recessed light hole saw available for them yet.

Often called "retro" cans out here, they work great once you get the hang of installation.

I tried all the holes saws, but got tired of bleeding drywall and plaster dust out of my eyes, so I went back to the keyhole saw. Believe it or not, I can out cut other guys that use the hole saws, and I NEVER over cut anymore. Please excuse the John-Henry-style bragging